So, after coming up with this idea while working on a book about tarantula care, I decided that it would make a good article/video/podcast. However, I'm sure that I'm missing some important terms (like substrate!). What am I missing?

So, after coming up with this idea while working on a book about tarantula care, I decided that it would make a good article/video/podcast. However, I'm sure that I'm missing some important terms (like substrate!). What am I missing?